OK, let's crack this. We're given 805 and our task is to multiply it by 81. Essentially, we'll be adding 805 to itself 81 times.
Step 1: 0 + 805 = 805
Step 2: 805 + 805 = 1610
Step 3: 1610 + 805 = 2415
Step 4: 2415 + 805 = 3220
Step 5: 3220 + 805 = 4025
Step 6: 4025 + 805 = 4830
Step 7: 4830 + 805 = 5635
Step 8: 5635 + 805 = 6440
Step 9: 6440 + 805 = 7245
Step 10: 7245 + 805 = 8050
Step 11: 8050 + 805 = 8855
Step 12: 8855 + 805 = 9660
Step 13: 9660 + 805 = 10465
Step 14: 10465 + 805 = 11270
Step 15: 11270 + 805 = 12075
Step 16: 12075 + 805 = 12880
Step 17: 12880 + 805 = 13685
Step 18: 13685 + 805 = 14490
Step 19: 14490 + 805 = 15295
Step 20: 15295 + 805 = 16100
Step 21: 16100 + 805 = 16905
Step 22: 16905 + 805 = 17710
Step 23: 17710 + 805 = 18515
Step 24: 18515 + 805 = 19320
Step 25: 19320 + 805 = 20125
Step 26: 20125 + 805 = 20930
Step 27: 20930 + 805 = 21735
Step 28: 21735 + 805 = 22540
Step 29: 22540 + 805 = 23345
Step 30: 23345 + 805 = 24150
Step 31: 24150 + 805 = 24955
Step 32: 24955 + 805 = 25760
Step 33: 25760 + 805 = 26565
Step 34: 26565 + 805 = 27370
Step 35: 27370 + 805 = 28175
Step 36: 28175 + 805 = 28980
Step 37: 28980 + 805 = 29785
Step 38: 29785 + 805 = 30590
Step 39: 30590 + 805 = 31395
Step 40: 31395 + 805 = 32200
Step 41: 32200 + 805 = 33005
Step 42: 33005 + 805 = 33810
Step 43: 33810 + 805 = 34615
Step 44: 34615 + 805 = 35420
Step 45: 35420 + 805 = 36225
Step 46: 36225 + 805 = 37030
Step 47: 37030 + 805 = 37835
Step 48: 37835 + 805 = 38640
Step 49: 38640 + 805 = 39445
Step 50: 39445 + 805 = 40250
Step 51: 40250 + 805 = 41055
Step 52: 41055 + 805 = 41860
Step 53: 41860 + 805 = 42665
Step 54: 42665 + 805 = 43470
Step 55: 43470 + 805 = 44275
Step 56: 44275 + 805 = 45080
Step 57: 45080 + 805 = 45885
Step 58: 45885 + 805 = 46690
Step 59: 46690 + 805 = 47495
Step 60: 47495 + 805 = 48300
Step 61: 48300 + 805 = 49105
Step 62: 49105 + 805 = 49910
Step 63: 49910 + 805 = 50715
Step 64: 50715 + 805 = 51520
Step 65: 51520 + 805 = 52325
Step 66: 52325 + 805 = 53130
Step 67: 53130 + 805 = 53935
Step 68: 53935 + 805 = 54740
Step 69: 54740 + 805 = 55545
Step 70: 55545 + 805 = 56350
Step 71: 56350 + 805 = 57155
Step 72: 57155 + 805 = 57960
Step 73: 57960 + 805 = 58765
Step 74: 58765 + 805 = 59570
Step 75: 59570 + 805 = 60375
Step 76: 60375 + 805 = 61180
Step 77: 61180 + 805 = 61985
Step 78: 61985 + 805 = 62790
Step 79: 62790 + 805 = 63595
Step 80: 63595 + 805 = 64400
Step 81: 64400 + 805 = 65205

So, 805*81 = 65205